/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.compiler;

import org.apache.jasper.JasperException;

import javax.servlet.jsp.tagext.FunctionInfo;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * This class defines internal representation for an EL Expression
 * <p>
 * It currently only defines functions.  It can be expanded to define
 * all the components of an EL expression, if need to.
 *
 * @author Kin-man Chung
 */

abstract class ELNode {

	public abstract void accept(Visitor v) throws JasperException;

	/**
	 * Child classes
	 */

	/**
	 * Represents an EL expression: anything in ${ and }.
	 */
	public static class Root extends ELNode {

		private final ELNode.Nodes expr;
		private final char type;

		Root(ELNode.Nodes expr, char type) {
			this.expr = expr;
			this.type = type;
		}

		@Override
		public void accept(Visitor v) throws JasperException {
			v.visit(this);
		}

		public ELNode.Nodes getExpression() {
			return expr;
		}

		public char getType() {
			return type;
		}
	}

	/**
	 * Represents text outside of EL expression.
	 */
	public static class Text extends ELNode {

		private final String text;

		Text(String text) {
			this.text = text;
		}

		@Override
		public void accept(Visitor v) throws JasperException {
			v.visit(this);
		}

		public String getText() {
			return text;
		}
	}

	/**
	 * Represents anything in EL expression, other than functions, including
	 * function arguments etc
	 */
	public static class ELText extends ELNode {

		private final String text;

		ELText(String text) {
			this.text = text;
		}

		@Override
		public void accept(Visitor v) throws JasperException {
			v.visit(this);
		}

		public String getText() {
			return text;
		}
	}

	/**
	 * Represents a function
	 * Currently only include the prefix and function name, but not its
	 * arguments.
	 */
	public static class Function extends ELNode {

		private final String prefix;
		private final String name;
		private final String originalText;
		private String uri;
		private FunctionInfo functionInfo;
		private String methodName;
		private String[] parameters;

		Function(String prefix, String name, String originalText) {
			this.prefix = prefix;
			this.name = name;
			this.originalText = originalText;
		}

		@Override
		public void accept(Visitor v) throws JasperException {
			v.visit(this);
		}

		public String getPrefix() {
			return prefix;
		}

		public String getName() {
			return name;
		}

		public String getOriginalText() {
			return originalText;
		}

		public String getUri() {
			return uri;
		}

		public void setUri(String uri) {
			this.uri = uri;
		}

		public FunctionInfo getFunctionInfo() {
			return functionInfo;
		}

		public void setFunctionInfo(FunctionInfo f) {
			this.functionInfo = f;
		}

		public String getMethodName() {
			return methodName;
		}

		public void setMethodName(String methodName) {
			this.methodName = methodName;
		}

		public String[] getParameters() {
			return parameters;
		}

		public void setParameters(String[] parameters) {
			this.parameters = parameters;
		}
	}

	/**
	 * An ordered list of ELNode.
	 */
	public static class Nodes {

		private final List<ELNode> list;
		/* Name used for creating a map for the functions in this
		   EL expression, for communication to Generator.
		 */
		String mapName = null;        // The function map associated this EL

		public Nodes() {
			list = new ArrayList<ELNode>();
		}

		public void add(ELNode en) {
			list.add(en);
		}

		/**
		 * Visit the nodes in the list with the supplied visitor
		 *
		 * @param v The visitor used
		 */
		public void visit(Visitor v) throws JasperException {
			Iterator<ELNode> iter = list.iterator();
			while (iter.hasNext()) {
				ELNode n = iter.next();
				n.accept(v);
			}
		}

		public Iterator<ELNode> iterator() {
			return list.iterator();
		}

		public boolean isEmpty() {
			return list.size() == 0;
		}

		/**
		 * @return true if the expression contains a ${...}
		 */
		public boolean containsEL() {
			Iterator<ELNode> iter = list.iterator();
			while (iter.hasNext()) {
				ELNode n = iter.next();
				if (n instanceof Root) {
					return true;
				}
			}
			return false;
		}

		public String getMapName() {
			return mapName;
		}

		public void setMapName(String name) {
			this.mapName = name;
		}

	}

	/*
	 * A visitor class for traversing ELNodes
	 */
	public static class Visitor {

		public void visit(Root n) throws JasperException {
			n.getExpression().visit(this);
		}

		@SuppressWarnings("unused")
		public void visit(Function n) throws JasperException {
			// NOOP by default
		}

		@SuppressWarnings("unused")
		public void visit(Text n) throws JasperException {
			// NOOP by default
		}

		@SuppressWarnings("unused")
		public void visit(ELText n) throws JasperException {
			// NOOP by default
		}
	}
}

